The present invention generally relates to test contactors used to establish an electrical interface between an integrated circuit (IC) device under test, and a circuit board, and more particularly, relates to the need to obtain a clean and dependable electrical contact between the spring probes of a contactor and the device under test (DUT).
The dependability of the electrical connection between the spring probes of the contactor and the contact pads or solder balls of a DUT package can be affected by the ability of the spring probes to penetrate through foreign material layers on the DUT's contact pads/solder balls (sometimes referred to herein as simply “contact pads”). Heretofore, spring probe contactors have been designed such that the spring probes contact the DUT's contact pads perpendicularly, that is, at a 90 degree angle relative to the DUT package, referred to herein as the z-axis. With the rapidly increasing pad/ball densities of IC devices, contact resistance requirements for testing devices are being rapidly reduced. With such reduction, the ability to achieve a good and dependable contact with the pads/balls of the DUT package has become a difficult problem, due the difficulty of penetrating the foreign material layers on the contact/ball surfaces. Resulting decrease in reliability in the contacts have led to costly retesting, and to the unnecessary rejection of tested IC devices.
The present invention overcomes the limitations of conventional contact designs by providing for an improved contactor capable of achieving good and dependable electrical contacts with the pads/solder balls of an IC package with a minimum contact force.